Abstract

Introducing water into pipelines for various applications, such as hydrotesting, long term layup, hydraulic fracturing, water injection, and other production related activities poses the threat of microbiologically influenced corrosion (MIC) when conditions are favorable. The focus of this paper is to outline a test method to evaluate the potential for MIC with untreated waters and subsequently assess the effectiveness of biocides to inhibit biofilm growth and mitigate MIC. The changes in the microbial activity, abundance, and diversity in the biofilm along with pitting and general corrosion rates on the carbon steel are used as evaluation techniques in this laboratory test method. The results of this work demonstrate the importance of using biofilms for biocide evaluations and could be used to support new industry standards for evaluating the effectiveness of biocides for MIC control, rather than basing performance on planktonic kill studies.

Introduction
Introduction to MIC

Microbiologically influenced corrosion (MIC) is a significant corrosion problem caused by microbial metabolism and microbial activity, assisting other abiotic processes and not just by the mere presence of microorganisms.1 Metabolic reactions of microorganisms in biofilms coupled with metal oxidation reactions are characteristic to MIC. It is therefore important to focus on the characteristics of the microbial community and corrosion when investigating the threat of MIC.2

Water is commonly introduced into pipelines and tanks for various applications such as hydrotesting, long term layup, hydraulic fracturing, water injection, and production related activities. In addition to the presence of microorganisms, water provides nutrients necessary for biofilm growth and corrosion and hence, the presence of water even in minimal amounts increases the likelihood of MIC. If left uncontrolled, MIC can ultimately result in leaks and ruptures of pipelines and tanks.3,4 Therefore, it is of utmost importance to monitor the threat of MIC and design appropriate mitigation methods to reduce the potential for MIC.

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2021. Association for Materials Protection and Performance (AMPP)
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